Currently, robotic frameworks must be built using multiple connection mechanisms including, for example, corner brackets, T brackets, fasteners with nuts, and/or welds for joining the frame members. A high efficiency structural system for building robots is needed to eliminate complications caused by these components. For example, one problem with using fasteners with nuts is that both front and rear sides of the components must be accessible to make the assembly. Often the interior of robot is obscured with the framework, motors, gearboxes, pneumatic cylinders and other actuators making it difficult to place and tighten a nut on the inside. Bolting a structure together with brackets adds unwanted cost, weight, and complexity to the structure. Brackets require added space in the structure, as compared to a directly bolted configuration. Consequently, as a load transfers from a frame member to a bracket and then back to another frame member, there is an undesirable reduction in stiffness and possibly strength compared to a directly bolted version.
While welding provides a direct attachment, it is not a precise fastening method. Prior to a weld being applied, parts must be aligned and clamped in place before welding, and even then the welding process will create substantial distortion in the finished structure. This is especially true with respect to welding aluminum alloys, since the coefficient of thermal expansion in aluminum is higher than most other commonly used metals such as steel and steel alloys. Typically, after a weld puddle cools and solidifies, it shrinks substantially. The shrinkage causes an undue amount of residual stress and distortion. As a further drawback, welding aluminum alloys also results in considerable reduction in the strength properties of the aluminum alloy in the heat affected area adjacent to the weld.
Although welding steel does not pose the same challenges as aluminum, most robotics builders avoid using heavier steel components for robot structures. Meeting weight limits in robot competitions with a steel frame is difficult since steel, with approximately 3 times the density of aluminum, has too much mass for a given shape.
Welding repairs and modifications are also problematic. Robots, particularly with respect to competitive builds, are often disassembled and reassembled several times to make modifications and repairs since the teams building the robots are usually on a steep learning curve. Multiple assembly and disassembly procedures are much more convenient with removable fasteners than with a welded structure.
The present disclosure provides new and novel solutions to overcome problems inherent in the prior art with a new and novel method and system allowing the ability to easily design and fabricate complex, lightweight, robust structures without the use of brackets, lugs, t-nuts, nuts or similar fasteners.